Precast Block and Installation System for Construction of Walls and Slabs

ABSTRACT

Precast blocks with a rectangular or quadrangular prism shape contain a normal weight hydraulic concrete casing, lightweight concrete or similar material, for building walls or slabs. The steel-reinforced blocks for walls, mezzanine or rooftop slabs have the length of the wall or slab to build. An acoustic, thermal-insulating lightweight material housed in the interior simultaneous provides for blocks sufficiently lightweight to transport and install manually on-site. For walls, the blocks are tongued and grooved on the top and bottom sides and placed horizontally one on top of the other using block or similar adhesive therebetween. In the corners or “T” intersections, blocks are alternatively placed and form armed headframes for stability and resistance. For blocks for slabs, the tongue and groove system is on the sides, installed one beside the other, using block or similar adhesive therebetween. Transversal rods to the slab are placed to avoid temperature retraction.

CROSS REFERENCE TO RELATED APPLICATIONS

None.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention is linked to the construction industry in general, particularly to the prefabrication of construction elements of walls and slabs for homes, schools, commercial spaces, hotels, and condominiums, among other applications. Specifically it is referred to a construction system based on precast normal weight hydraulic concrete quadrangular or rectangular prism-shaped blocks, lightweight concrete, mortar, cement paste or any other material for similar constructions that can be used reinforced in order to support the loads of its own weight and working loads under which it is submitted. It includes in its interior, thermal and acoustic insulating materials. The precast blocks will be the length of the wall or width of the slab.

2. Description of the Art

Currently, in construction, there are numerous precast blocks for on-site construction of walls and slabs, different materials, both natural as well as artificial ones with quite diverse physical and mechanical properties.

Generally, blocks are used to fabricate walls, which are relatively small pieces that when installed produce many joints to be glued together using a mortar, with the consequent waste of material and a large volume of labor, for example: pressed hollow blocks of cement mortar mixed with sand or pumice mortar, hollow pressed clay blocks, pressed cinder blocks of cement mortar mixed with sand, baked clay or clay solid bricks, clay hollow bricks or pressed and baked clay bricks, thermoclay, pressed soil bricks or cinder blocks, adobe bricks, Hebel blocks, besides other of similar types. There are also larger precast armed hydraulic concrete blocks, that due to their weight and size the use of cranes is needed for their installation or lifting, ending in higher costs and complicated maneuvers, along with troubles in the constructions joints due to cracking. Another precast system uses 2-sides Durock sheets or adhered fiber cement expanded polystyrene blocks of the length and thickness of the wall and with a modulated block banking to its height. Even when it is reinforced with mortar sunken rods directly embedded into the polystyrene block, this system is quite fragile. It neither withstands heavy loads nor can it be directly pounded and it is not better than a drywall or Durock system.

To fabricate slabs, cement-sand pressed hollow blocks are used or cement-pumice stone or pressed clay hollow blocks or expanded polystyrene blocks are also used, forming infill blocks as lightening elements for concrete reticular slabs. Cement-sand or cement-pumice stone hollow pressed and baked clay arch-shaped blocks are also used; all these sustained between beams, whether of concrete or steel, into which a layer of hydraulic concrete compression layer must be poured. Of course there are the armed hydraulic concrete precast slab blocks, either prestressed or poststressed, which, given their weight and footprint, also need cranes for their lifting and installation.

BRIEF SUMMARY OF THE INVENTION Objectives of the Invention

A major objective of the present invention is the obtaining of a precast block system for construction of walls and slabs that is sufficiently lightweight for blocks forming the walls or slabs to be easily and rapidly manually installed but being of a size that covers the length of the walls and bay of the slabs of any size of house, schoolroom, hotel room or condominium, among other applications. Its block height will be modulated at the height of the wall layout and at the height of the closure of doors and windows of the same wall. In the case of the slabs, whether mezzanine levels or rooftops, they can be modulated to adjust to the width of the slab.

Another objective not less important is to bring safety and stability of the constructions, even in zones or seismic regions or susceptible to strong winds or snowfalls. The walls will be structured in the corners and in the crossing of the walls through the use of sunken steel rods in the extremes of the blocks making the walls, forming the headframes, using steel rod abutments installed in the joints between the blocks. The reinforcement area will be calculated to provide stability to the construction of one or several levels. The blocks that form the mezzanine or rooftop slabs will be reinforced with steel electrowelded wire mesh or rods to withstand their own loads and the working load to which they will be submitted.

Another objective of the present invention is to offer comfort and energy savings inside houses, schoolrooms, hotels, and condominiums, among other applications, given the thermal and acoustic insulation provided by normal weight hydraulic concrete, lightweight concrete, any type of concrete, mortar or cement paste and the thermal and acoustic insulating materials the blocks are made of to form the mezzanine or rooftop walls and slabs.

Another objective of the present invention is for the walls and slabs—formed by normal weight hydraulic concrete blocks, lightweight concrete, mortar or cement paste and the thermal and acoustic materials—to be of an apparent finish to avoid thick mortar plasters. This results in savings on materials, labor and execution time plus offers the advantage that the surfaces of the walls and slabs allow nails, grooves, cuts or patches.

Another objective of the present invention is to offer safety due to the integrity of the walls and slabs formed by normal hydraulic concrete blocks, lightweight concrete or mortar, thermal and acoustic insulating materials and fire resistance provided by the superficial layer of concrete.

Another objective of the present invention is to provide conduits for electric installations and pipes less than 2″ in diameter. The conduits are also for hydraulic and sanitary installations. The conduits are embedded inside the walls and slabs formed by the normal weight hydraulic concrete precast blocks, whether of lightweight concrete, mortar or paste and kept protected by the thermal and acoustic insulating materials.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Description of Normal Weight Hydraulic Concrete Precast Blocks, Lightweight Concrete, any Type of Concrete, Mortar or Cement Paste, Steel Reinforcement and Thermal and Acoustic Insulating Materials for the Fabrication of Mezzanine and Rooftop Walls and Slabs.

The characteristic details of the present invention are clearly depicted in the following description and in the drawings accompanying it as illustrations of the same in the shown figures.

FIG. 1 shows an isometric view with all the elements that make up the precast block for walls.

FIG. 2 shows a bottom view of the precast block for walls.

FIG. 3 shows a top view of the precast block for walls.

FIG. 4 shows a vertical longitudinal cut of the precast block for walls.

FIG. 5 shows a transversal cut of the ends of the precast block for walls.

FIG. 6 shows a transversal cut of the central part of the longitudinal body of the precast block for walls.

FIG. 7 shows a transversal cut with electric installation ducts in the precast block for walls.

FIG. 8 shows a transversal cut with steel rod reinforcement in the precast block for walls.

FIG. 9 shows a vertical cut of the union of blocks to form a wall.

FIG. 10 shows a vertical cut of the reinforcement in the union of blocks to form the intersection, whether in a 2 corner walls at right angle or in a 3 corner walls also at right angle.

FIG. 11 shows an isometric view of the union of precast blocks to form two corner walls at right angle.

FIG. 12 shows a horizontal cut of the reinforcement of the union of precast blocks to form an intersection of three walls at right angle.

FIG. 13 shows a horizontal cut of the reinforcement of the union of precast blocks to form an intersection of two corner walls at right angle.

FIG. 14 shows a horizontal cut of the reinforcement of the union of precast blocks to form an intersection of three walls at right angle.

FIG. 15 shows an isometric view with all the elements that form the precast block for slabs.

FIG. 16 shows the side view with a tongue and groove dowel system of the precast block for slabs.

FIG. 17 shows the side view with a tongue and groove socket system of the precast block for slabs.

FIG. 18 shows a horizontal longitudinal cut of the precast block for slabs.

FIG. 19 shows a vertical longitudinal cut of the precast block for slabs.

FIG. 20 shows a transversal cut of the precast block for slabs.

FIG. 21 shows a transversal cut with electric duct of the precast block for slabs.

FIG. 22 shows a transversal cut of the union of precast blocks to form a slab.

FIG. 23 shows an isometric view of the union of the blocks for slabs with the retraction and temperature reinforcement.

DETAILED DESCRIPTION OF THE INVENTION

The present invention consists of a precast block and installation system for the construction of normal weight hydraulic concrete, lightweight concrete, any type of concrete, mortar or paste, electromesh reinforcement and/or steel rods and thermal and acoustic insulating materials including hollow ones for mezzanine and rooftop walls.

Referring to FIGS. 1-8, the precast block for construction of walls is a rectangular or quadrangular prism-shape block the same length of the wall (L) to which it is a part. It has a base (B) with a measure that depends on the load to bear and the thickness of the thermal insulation that is required. It has a block height (D) that depends on the modulation given by the height of the wall and the height of the closure and parapets of doors and windows.

Referring to FIGS. 1, 5, 6 and 7, the precast block for walls consists of a casing (1) of variable thickness made of normal weight hydraulic concrete, lightweight concrete, any type of concrete, mortar or paste. As reinforcement, between the exterior wall (22) and the interior wall (6) of the casing there is a steel wire of quadrangular or rectangular electromesh tube (4) similar to the shape of the exterior casing of the precast block lengthwise (L) that can be reinforced or replaced with straight steel rods (7) (see FIG. 8) and abutments also made of steel rods having the same tubular shape lengthwise (L) as the precast block for construction of walls. On the top side of the casing of the precast block for walls and as a part thereof, there is an aligned dowel-shape protrusion (2) on the block lengthwise (L) of the tongue and groove or assembly dowel, except for at both ends at a length of (2B) (see FIG. 3). On the bottom side of the casing and as a part thereof, there is a socket-shape groove (3) corresponding to the tongue and groove lengthwise (L).

Referring to FIGS. 1-2, inside the block, the hollow internal space—which has acquired a quadrangular or rectangular prism-shape defined by the interior wall (6) of the casing—can be filled with a lightweight thermal and acoustic insulating material (5) or with air. Said hollow runs throughout the block, except for at both ends, at a distance of (2B), from the edges of the block itself, as shown in FIG. 3. In each one of the ends of the block, two vertical 2″ up to 4″ diameter cylinder shape holes (11) are located, same height of the block height (D) located at the center of the base (B) and at a distance from the edges of 0.5 B and 1.5 B, respectively, as shown in FIG. 2.

Still referring to FIG. 1, the block has a groove (18) transversal to the socket portion of the tongue and groove at a distance of 0.5 B from the center of the groove to each edge of the bottom side of the precast block for construction of walls to fasten a portion of the abutment of the headframes formed in the corners or “T” intersections of the walls (see also FIGS. 4, 11, 12).

For the fabrication of the wall, the precast blocks will be installed one on top of each other to set the tongue and groove system joined with an adherent material, whether cement base mortar, block adhesive or similar adhesive (15) (see FIGS. 9, 10, 13, 14), leaving precast blocks for walls with electric ducts at the corresponding height, whether for electric outlet, switches or sconces. At the closures height, one or several precast blocks for walls will be installed using straight steel rods (7) as extra reinforcement besides the electromesh (4), as shown in FIG. 8 (see also FIGS. 9, 15, 20, 21, 22, 23). The first base block will be set on top of the foundation through an adherent material that includes a waterproofing system to avoid moisture from rising up the wall (20) (see FIGS. 9 and 10).

Referring now to FIGS. 11, 12, 13 and 14, in the unions of two corner walls (FIGS. 11, 13) or three walls in “T” shape (FIGS. 12, 14) at right angle, the reinforced connection is done by overlapping the blocks in an alternate way setting them with cement base mortar, block adhesive or similar adhesive (15). Vertical hollows (11) are then matched starting from the ends of the blocks to form the headframes with three vertical steel rods (8) inserted in the hollows (11) in the case of corner walls with steel abutments (9) in each horizontal joint between blocks (See FIGS. 11, 13), and four vertical steel rods (8) inserted in the hollows in case of “T” walls with steel rod abutment (10) in each horizontal joint between blocks (See FIGS. 12, 14).

The embedding of the headframes will be done using vertical rods (8) housed inside the vertical hollows (11) from foundation up to mezzanine or rooftop precast slabs. Vertical hollows (11) are filled with a grout (14) or similar material, as shown in FIGS. 13 and 14.

Referring now to FIGS. 16, 17 and 18, the precast block for the construction of mezzanine and rooftop slabs is comprised by a rectangular or quadrangular prism shape concrete block of the width of the slab lengthwise (L) plus the supports, a width in the base (B′) depending on the modulation of the slab transversal width and a block height (D′) depending on the measure of the calculation memory, specifications, along with the insulation that is required.

Referring now to FIG. 15, the precast block for walls consists of a casing (1) of variable thickness made of normal weight hydraulic concrete, lightweight concrete, any type of concrete, mortar or paste. As reinforcement, between the exterior wall (22) and the interior wall (6) of the casing there is a steel wire quadrangular or rectangular electromesh tube (4) similar to the shape of the exterior casing of the precast block that can be reinforced or replaced with longitudinal steel rods (7) and abutments throughout the length of the block (L′). The reinforcement areas will depend on the calculation memory run to resist its own loads and working loads on the slab. As shown in FIGS. 20 and 21, on one lateral side of the casing and as a part thereof, there is a dowel protrusion (2) tongue and groove lengthwise (L′) on the block for the slab. On the other lateral side of the casing and as part of it, there is a socket groove (3) of the tongue and groove lengthwise of the same block.

Inside the precast block for slabs, the hollow internal space which has acquired a rectangular or quadrangular prism shape defined by the interior wall (6) of the casing, can be filled with an acoustic and thermal insulating lightweight material (5) or with air, lengthwise (See e.g., FIGS. 20 and 21).

Referring now to FIGS. 15, 16, 17 and 19, there are between ¾″ or 2″ width and depth transversal longitudinal grooves (21) on the top compression layer of the precast block for slabs with the necessary separation according to the retraction calculation due to temperature changes. Steel rods (19) will be placed in the same grooves and filled with grout or similar mortar.

The precast block for slabs can house a duct for electric installations inside the lightweight material prism. This can be placed according to the needs of the mezzanine or rooftop slab.

For fabricating a mezzanine or rooftop slab, concrete precast blocks will be set between the walls or support beams, one beside the other matching pin and tail of the tongue and groove system, gluing them through a cement base adhesive, block adhesive or similar one (15) leaving the block with the electric duct where it is projected and by embedding the electrical outlet box, (13) on the block, as shown in FIG. 21. 

I claim:
 1. A precast block for construction as those made with aggregates and cementitious materials for use on walls, characterized by having a quadrangular or rectangular prism shape that contains a casing, which is part of it, 0.2″ up to 4″ thickness normal weight hydraulic concrete, lightweight concrete or any other type of concrete, mortar, paste or any construction material using an agglomerating agent, aggregates and water, with a compression resistance of at least 356 lb/in²; with a length (L) of the wall that will become a part of and which range can be between 6.3″ up to 66 ft; with a width (B) that will depend of the load to bear and the thickness of the required insulation and that can have between 1″ up to 2 ft; a block height (D) that will depend on the modulation per the height of the wall, the heights of closures and parapets of doors, windows and wall openings, this block height will be between 6″ or up to 4 ft height.
 2. A precast block for construction as those made with aggregates and cementitious materials for their use on walls according to claim 1, characterized by having on the top side of the casing of the precast block for walls and forming a part of it and of the same material, a dowel tongue and groove protrusion or assembly tongue, either isosceles trapezoid-shape, square, rectangular, semicircular, triangular or any polygonal that serves for the before described purpose, aligned throughout of the block, except for a length of (2B) on each end of the block itself, with a block height from 0.004″ up to 4″ and a thickness in its base from (0.1B) up to (1B) of the precast block. On the bottom side of the precast block for walls casing and as a part of it and of the same material, there is a groove socket shape of the tongue and groove or slot matching the shape of the dowel, with the measure of block height and width in its base to fit into another similar block lengthwise (L) and to form the wall by setting them and gluing them using a cement-sand mortar, block adhesive or similar adhesive.
 3. A precast block for construction as those made with aggregates and cementitious materials for their use on walls, according to claim 2, characterized by a steel reinforcement that will be a tubular electromesh of rectangular or square transversal section, reinforced or replaced by straight steel rods and abutment-shaped. Said reinforcement will be placed inside the thickness between interior and exterior casing walls lengthwise (L). The reinforcement area of the longitudinal steel will be between 0.0005 and 0.0533 of the area of the precast block for walls transversal section; the area of the transversal steel reinforcement will be between 0.16 in² and 1.5 in² per linear feet of the precast block for walls, throughout the length of the block (L).
 4. A precast block for construction as those made with aggregates and cementitious materials for its use on walls according to claim 3, characterized by the fact that throughout the precast block in the longitudinal hollow space (L-2B), confined within the precast block for wall casing, there is an acoustic and thermal insulating material (5), which will be expanded polystyrene, polyurethane foam, vermiculite, mineral or glass stone wool, cellulose or polyethylene foam, aerogel, air or any other insulating material, which will acquire the same shape of the hollow, being kept encapsulated inside the precast block lengthwise (L), except for the ends of the block, at a distance from the edge of (2B).
 5. A precast block for construction as those made with aggregates and cementitious materials for their use on walls, according to claim 4, characterized by the fact that each one of the two ends of the precast block for walls have, transversal to the wall length, two cylindrical perforations, 2″ up to 4″ in diameter vertical perforations at an equal height of the block height (D), placed at the center of the base (B) and at a distance from the center of each hole to each end of the precast block of (0.5B) and (1.5B), respectively.
 6. A precast block for construction as those made with aggregates and cementitious materials for their use on walls, according to claim 5, characterized by: a lengthwise transversal groove (18) placed in the base of each end of the precast block for walls with a socket of the tongue and groove; of a width from 2″ up to 4″, of length equal to the base and ¾″ in height, measured from the sides to the base (B).
 7. A precast block for construction as those made of aggregates and cementitious materials for their use on walls, according to claim 6, characterized by the fact that they can contain ½″ up to 1½″ in diameter poliducts, housed inside the interior space confined by the interior wall of the block casing and at half the block height (D).
 8. A fabrication method of walls based on precast blocks for construction as those made with aggregates and cementitious materials, according to claims 1 to 7, characterized by the following: I) Blocks are vertically placed at the same length (L) of the wall or jamb. II) Blocks are set and joined using a mortar. III) At the electrical outlet, switch or sconce levels, the blocks with ducts are placed. IV) At the height of the closures of doors, windows or larger wall openings, reinforced blocks are installed. V) In the union of two corner walls or three “T” shape walls, both at right angle, overlapped blocks in alternate way are placed. VI) In the vertical cylindrical hollows of the ends of the blocks, three vertical rods in case of the corner walls or four vertical rods in the case of “T” walls are placed. VII) Steel rods, transversal to the vertical rods are placed forming abutments. VIII) Abutments will be set in between the joints of the blocks forming the headframes. IX) The vertical cylindrical hollows with rods and abutments will be filled with a grout or similar material. X) The embedding of the headframes into foundation is achieved by elongating the rods of the headframes.
 9. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that said precast blocks are vertically placed throughout the length (L) of the wall or jamb, one on top of the other, matching tongue and groove dowels and sockets.
 10. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that while setting the blocks one on top of another, they are glued with a cement base mortar, block adhesive or similar adhesive lengthwise (L).
 11. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that at the height of the electric outlet, switch or sconce, the corresponding blocks for walls are placed with ducts for the electrical installation.
 12. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that at the height of the closures of doors, windows or even larger wall openings, one or several precast blocks for walls will be placed with the necessary reinforcement steel area.
 13. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that in the union of two corner walls or three “T” walls at right angle, is made by overlapping the precast blocks for walls in alternate way, setting and gluing them with cement base mortar, block adhesive or similar adhesive, matching the vertical cylindrical hollows of the ends of the precast blocks for walls to form the headframes.
 14. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that the vertical cylindrical hollows of the ends of the precast blocks for walls are armed using three vertical rods in case of corner walls or four vertical rods in case of “T” walls, inserting the rods into the vertical cylindrical hollows.
 15. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that transversal steel rods as abutments are installed, joining the vertical steel rods.
 16. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that the abutments will be placed in the joints between precast blocks forming reinforcement headframes for the walls.
 17. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that a part of the abutments will be housed in the transversal grooves located in the base (B) of the precast blocks for walls.
 18. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that the vertical cylindrical hollows along with the rods and steel abutments will be filled with a grout or a very fluid, easy to handle mortar or similar material with a compression resistance of more than 2844 lb/in^(t), which has no contraction due to drying.
 19. A fabrication method of walls based on precast blocks for construction as those made of aggregates and cementitious materials, according to claim 8, characterized by the fact that the embedding of the armed headframes into the foundation of corner or “T” intersections of the walls made with precast blocks will be done by elongating the vertical steel rods down into the necessary depth, according to the type of foundation or system.
 20. A precast block for construction as those made of aggregates and cementitious materials for its use on lightened slabs, characterized by having a quadrangular or rectangular prism shape, that contains a casing that forms a part of it, 0.2″ up to 6″ of normal weight hydraulic concrete, lightweight concrete or any other type of concrete, mortar, paste or any material for construction that is made of agglomerating agent, aggregates and water, which has a compression resistance of at least 356 lb/in^(t); with the length of the width of the slab plus supports (L′) of up to 66 ft, a base width (B′) depending on the modulation of the transversal width of the slab from 4″ up to 6.6 ft; a block height (D′) which will be between 4″ and 2 ft depending on the structural calculation and the needs of insulation.
 21. A precast block for construction as those made of aggregates and cementitious materials for its use on lightened slabs, according to claim 20, characterized by having on one of the lateral sides a casing that is part of the precast block for slabs and of the same material, a dowel protrusion of the tongue and groove or assembly tongue, either of isosceles trapezoid shape or square, rectangular, semicircular, triangular or any polygonal which serves for such previously described purpose, aligned throughout the block, with a block height from 0.04″ up to 6″ and a base width from (0.1 D′) up to (1.0 D′) of the precast block for slabs; on the other opposing side of the casing of the rectangular, or square precast block for slabs, forming a part of it, of the same material and lengthwise (L′), there is a socket-shape groove of matching shape to the dowel of the tongue and groove, of the same measures of the block height and width in its base to fit into another similar block lengthwise (L′) to form the slab by setting them and gluing them using a cement-sand mortar, block adhesive or similar adhesive.
 22. A precast block for construction as those made of aggregates and cementitious materials for its use on lightened slabs, according to claim 21, characterized by having a steel reinforcement that will be a rectangular or square section of tubular electromesh, reinforced or replaced by straight steel rods and in the shape of abutments, said reinforcement will be placed inside the thickness between the exterior and interior walls of the block casing and throughout its length (L′); being the longitudinal reinforcement steel area, whether electromesh or rod. Said reinforcement will be of 0.0012 and 0.068 of the area of the transversal section of the precast block for slabs; the steel area, whether comprised by the electromesh or the rods of the abutments will be between 0.16 in² and 2.62 in² per linear feet of the reinforcement of the precast block for slabs, lengthwise (L′).
 23. A precast block for construction as those made of aggregates and cementitious materials for its use on lightened slabs, according to claim 22, characterized by the fact that throughout the length of the precast block in the hollow space confined inside the casing of the precast block for slabs, there is an acoustic and thermal insulating material which will be expanded polystyrene, polyurethane foam, vermiculite, mineral or glass stone wool, cellulose or polyethylene foam, aerogel, air or any other insulating material, which will acquire the same shape as the hollow, being kept encapsulated inside the precast block for slabs lengthwise (L′).
 24. A precast block for construction as those made of aggregates and cementitious materials for its use on lightened slabs, according to claim 23, characterized by the presence of 1 3/16″ width, 0.40″ to 2″ depth grooves, located on the top side and transversally to length (L′) of the precast block for slabs; the separation between the grooves will be between 8″ and 4 ft, depending of the reinforcement calculation to counteract the retraction per slab temperature.
 25. A precast block for construction as those made of aggregates and cementitious materials for its use on lightened slabs, according to claim 23, characterized by the fact that it can contain a ½″ to 1½″ in diameter poliduct which will be housed inside the interior space confined by the interior wall of the block casing and placed at the center of the base (B′).
 26. A fabrication method of lightened slabs based on precast blocks for construction as those made with aggregates and cementitious materials, according to claims 20 to 25, characterized by the following facts: I) Precast blocks are horizontally placed over supports by fitting the lateral tongue and groove systems, for dowel and socket to match. II) Precast blocks are glued together at the tongue and groove systems of the lateral sides with a mortar, lengthwise (L′). III) Steel rods are placed in the grooves located on the top side of the precast blocks. IV) The grooves are filled with rods set with a grout or similar material.
 27. A fabrication method of lightened slabs based on precast blocks for construction as those made with aggregates and cementitious materials, according to claim 26, characterized by the fact that they are horizontally placed on their base (B′), over the supports so the lateral tongued and grooved dowel and socket match.
 28. A fabrication method of lightened slabs based on precast blocks for construction as those made with aggregates and cementitious materials, according to claim 26, characterized by the fact that the precast blocks are set and glued together with a cement base mortar, block adhesive or similar adhesive, lengthwise (L′).
 29. A fabrication method of lightened slabs based on precast blocks for construction as those made with aggregates and cementitious materials, according to claim 26, characterized by the fact that steel rods are placed to avoid the temperature retraction in the grooves located on the top side of the precast blocks for slabs.
 30. A fabrication method of lightened slabs based on precast blocks for construction as those made with aggregates and cementitious materials, according to claim 26, characterized by the fact that the grooves with rods are filled with a non-ferrous grout or very fluid mortar, easy to handle, with a minimum compression resistance of 2844 lb/in² without contraction due to drying. 